T 

357 

Fa 


HOW  TO  MAKE 

PAT  ENT 
DRAWINGS 


A  BRIEF  TREATISE  ON 
PATENT  DRAFTING, 
FOR  THE  USE  OF 
STUDENTS,  DRAFTSMEN 
AND  INVENTORS 


Patent  Drafting  Syndicate 

Schenectady  1919  New  York 


Hie 


How  to  Make  Patent 
Drawings 


A  Brief  Treatise  on    Patent  Drafting  for  the  Use  of 
Students,  Draftsmen  and  Inventors 


By 
L.  H.  FULMER 


Published  by 
PATENT  DRAFTING  SYNDICATE 

Schenectady,  N.  Y. 
1919 


COPYRIGHT,  1919, 

BY 

LESTER  H.  FULMER 
SCHENECTADY,  N.  Y. 


PREFACE 

A  great  many  books  have  been  written  on  drawing, 
both  mechanical  and  architectural,  but  to  my  knowl- 
edge very  few,  if  any,  have  ever  given  information  in 
regard  to  the  making  of  Patent  drawings,  excepting 
of  course  the  II.  S.  "  Rules  of  Practice."  In  this 
progressive  period,  when  there  are  so  many  inventions 
being  discovered  and  so  many  patents  being  secured  to 
protect  the  same,  there  is  naturally  a  demand  for  good 
Patent  Draftsmen.  As  every  patent  issued  requires 
drawings,  and  the  U.  S.  Patent  Office  will  accept  only 
drawings  which  are  made  by  men  skilled  in  the  art,  and 
made  under  certain  rules,  I  think  that  a  book  disclos- 
ing information  on  this  subject  will  be  very  useful,  not 
only  to  the  man  wishing  to  fit  himself  to  hold  a  position 
as  draftsman,  but  also  to  the  inventor  who  desires  to 
make  his  own  drawings,  either  to  save  himself  the 
expense,  or  because  he  is  so  located  as  to  be  unable  to 
secure  the  services  of  a  good  man. 


451894 


CONTENTS 

PREFACE 

CHAPTER  .  PAGE 

I.  Instruments  and  Materials 5 

II.  Use  of  Instruments 13 

III.  Penciling  the  Drawing 18 

IV.  Inking  the  Drawing 25 

V.  Sections  and  Section  Lining 28 

VI.  Outline  Shading 31 

VII.  Surface  Shading 34 

VIII.  Lettering  the  Drawing 36 

IX.  Sketching 37 

X.  Care  of  Instruments 39 

XI.  Blue  Printing,  etc 41 

XII.  Useful  Hints.                                                      ,  43 


CHAPTER  I 
INSTRUMENTS  AND  MATERIALS 

Introduction. — In  this  chapter  I  have  listed  instru- 
ments and  materials  necessary  to  make  a  first  class 
Patent  drawing,  and  they  should  be  secured  before 
attempting  any  work.  They  can  be  purchased  at  most 
Art  stores,  or  if  desired,  can  be  ordered  through  the 
mail  from  firms  dealing  exclusively  in  draftsman's 
supplies.  To  the  man  just  starting  this  work  the  in- 
struments may  seem  an  expensive  investment,  but  if 
good  instruments  are  bought  this  is  not  so,  as  they  will 
last  a  lifetime,  and  the  draftsman  is  always  sure  of 
securing  the  best  results  in  his  work.  The  beginner 
should  never  hinder  himself  by  using  instruments  of 
an  inferior  grade,  as  the  accuracy  and  speed  of  patent 
drawings  as  well  as  the  finish  depends  to  a  great  extent 
on  the  quality  of  the  instruments. 

The  instruments  and  materials  I  have  divided  into 
two  lists,  the  first  consisting  of  those  which  are  abso- 
lutely necessary,  and  the  second  those  not  necessary 
but  good  to  have  for  certain  work. 

The  first  list  consists  of  drawing  board,  drawing 
paper,  thumb  tacks,  pencil,  ink,  erasers  (pencil  and 
ink),  tee-square,  30°  and  45°  triangles,  scale,  irregular 
curve,  compass  (with  pen  and  pencil  point,  and  length- 
ening bar),  dividers,  bow  dividers,  bow  pencil,  bow 
pen,  and  ruling  pen  (medium  size). 

In  Plate  1  (2)  illustrates  drawing  board,  (3)  draw- 
ing paper,  (4)  thumb  tack,  (5)  45°  triangle,  (6)  30° 
triangle,  and  (7)  tee-square. 


The  second,  list  consists  of  proportional  dividers, 
erasing  shield,  crow  quill  pen,  transfer  sheet,  stylus, 
pencil  pointer,  burnisher,  cleaning  eraser,  and  a  small 
ruling  pen. 


o         o 

o 
o        o 


k 


PLATE  1 


Drawing  Board. — The  drawing  board  is  a  rectangu- 
lar board  on  which  is  fastened  the  paper.  Usually  it 
is  made  of  white  pine  about  %"  or  %"  thick,  and  with 
the  grain  running  the  long  ways  of  the  board.  The 
most  convenient  size  for  patent  work  is  13"  x  18".  It 
must  never  be  less  than  10%"  x  15y2".  The  front  face, 
that  is,  the  working  surface,  should  be  smooth  and  per- 
fectly flat.  The  four  edges  of  the  board  should  form  a 
perfect  rectangle,  or  at  least  the  adjacent  edges  at  the 
lower  left  hand  corner  should  be  at  right  angles  to  each 
other.  It  is  generally  used  with  the  short  sides  at  top 
and  bottom. 


Dr diving  Paper. — The  paper  must  be  pure  white 
with  a  smooth  calendered  surface  and  must  have  a 
thickness  to  equal  three-ply  Bristol  board.  Of  course 
the  better  the  quality  the  more  easily  erasures  may  be 
made.  The  size  of  the  sheets  must  be  10"  x  15".  For 
patent  work  I  recommend  Reynolds  Bristol  board  of 
three  ply,  which  comes  in  sheets  about  12%"  x  15%", 
allowing  a  margin  outside  the  cutting  lines  of  the  draw- 
ing on  which  you  can  try  your  pens  when  inking.  Pat- 
ent firms  usually  furnish  their  workmen  with  paper. 

Tlfiuinb  Tacks. — Thumb  tacks  are  used  to  fasten  the 
sheet  of  paper  to  the  drawing  board.  Those  made  of 
one  piece  of  hard  steel  with  a  flat  head  and  fine  needle 
point  are  the  best.  They  are  very  inexpensive  and  a 
dozen  of  the  best  quality  should  be  secured. 

Pencil. — The  drawing  pencil  for  laying  out  all  draw- 
ings should  be  of  good  quality ;  not  too  hard  as  it  will 
make  indentures  in  the  surface  of  the  paper,  and  in 
case  of  an  erasure  cannot  be  removed ;  nor  should  it  be 
too  soft,  as  it  will  wear  away  quickly  and  it  would  be 
impossible  to  secure  sharp  lines.  I  recommend  a  pen- 
cil of  HHHH  hardness.  This  should  be  sharpened  to 
a  long  conical  point  secured  by  holding  the  lead  at  an 
angle  to  a  piece  of  sandpaper  or  emery  cloth  and  draw- 
ing it  back  and  forth  at  the  same  time  revolving  the 
same.  While  penciling  the  drawing  the  point  should 
be  watched  and  when  it  becomes  rounded  or  blunt 
should  be  touched  up  on  the  sandpaper. 

The  pencil  should  be  held  vertical  or  nearly  so  and 
should  be  pressed  on  the  paper  lightly.  If  inclined  at 
all  it  should  be  in  the  direction  in  which  it  is  moved. 

Ink. — India  waterproof  ink  is  the  best  for  this  work, 
and  I  recommend  that  put  on  the  market  by  Higgins. 
This  ink  flows  freely  and  presents  a  perfectly  black 
line.  It  comes  in  a  bottle  with  a  short  quill  in  the 


8 

stopper.  By  means  of  this  quill  ink  is  easily  placed 
between  the  blades  of  the  pens  and  compasses.  Be 
sure  before  using  to  shake  the  bottle  well  as  it  will 
settle  and  is  liable  to  be  thick  near  the  bottom.  If  it 
should  become  too  thick  to  flow  properly  it  can  be 
thinned  by  adding  a  few  drops  of  ammonia. 

Erasers. — For  a  pencil  eraser  a  soft  pliable  rubber 
should  be  used.  Do  not  bear  on  the  paper  but  rub 
softly.  Pressure  on  the  rubber  does  not  remove  the 
line  any  sooner. 

For  ink  eraser,  use  a  stiff  rubber  with  very  little  grit 
in  it.  For  most  work  a  pencil  eraser  will  answer  the 
purpose.  It  will  take  a  little  longer,  but  the  surface 
of  the  paper  will  not  be  injured  as  it  might  by  a  hard 
pressure  on  the  ink  eraser. 

Tee-Square. — The  tee-square  is  used  as  an  edge  on 
which  to  draw  horizontal  lines;  and  as  a  surface  to 
place  the  triangles  against  for  drawing  straight  lines 
in  oblique  and  vertical  directions.  This  instrument 
derives  its  name  from  its  shape  which  is  that  of  the 
letter  "  T."  It  consists  of  two  parts:  the  blade,  and 
the  stock.  The  horizontal  part  of  the  letter  "T"  is 
the  stock  and  the  vertical  part  the  blade.  They  are 
joined  together  at  right  angles  to  one  another.  The 
stock  is  placed  against  the  working  edge  of  the  board 
and  the  lines  are  drawn  along  the  edge  of  the  blade. 
The  tee-square  for  this  w^ork  should  be  18"  long  and 
preferably  of  wood  with  celluloid  edges. 

To  use,  grasp  the  tee-square  near  the  'center  of  head 
with  the  left  hand,  and  slide  the  inner  edge  of  the  head 
against  the  edge  of  the  board,  always  making  sure  the 
edge  is  in  perfect  contact,  otherwise  the  lines  would 
not  be  parallel. 

30°  and  45°  Triangles. — Triangles  are  used  as  a 
guide  for  the  pencil  or  ruling  pen  in  drawing  lines  at 


an  angle  to  the  tee-square.  They  are  always  used  to 
make  section  lines.  Those  made  of  celluloid  are  to  be 
most  recommended  for  this  work,  as  the  draftsman  is 
able  to  see  through  the  transparent  material  and  thus 
work  to  better  advantage.  There  are  two  triangles 
needed  in  this  work,  one  known  as  the  45°  and  the 
other  the  30°.  They  both  have  one  right  angle,  and 
in  addition  the  one  has  two  45°  angles,  the  other  one 
30°  angle  and  one  60°  angle.  The  most  convenient 
size  for  this  work  are  those  with  legs  about  6"  to  8" 
long. 

To  use,  place  triangle  against  the  upper  edge  of  tee- 
square  and  hold  in  perfect  contact  with  the  same  by 
the  first  three  fingers  of  left  hand,  while  the  rest  of 
the  hand  holds  the  tee-square  firmly. 

Scale. — The  scale  is  used  principally  to  mark  off 
accurately  the  cutting  out  lines  and  the  border  lines 
of  the  drawing.  It  is  also  used  in  cases  in  which  the 
draftsman  has  a  model  or  blue  prints  from  which  he 
wishes  to  secure  dimensions  or  from  which  he  wishes 
to  make  a  drawing  at  a  reduced  scale.  The  12"  box- 
wood scale  is  the  best  for  this  work. 

Irregular  Curve. — Irregular  curve  (sometimes  called 
French  curve)  is  used  to  draw  curved  lines  that  can- 
not be  made  conveniently  with  a  compass  or  other 
instruments.  They  are  of  wood,  hard  rubber  or  cellu- 
loid. Celluloid  is  the  best.  The  curve  to  be  laid  out 
is  usually  constructed  by  locating  a  number  of  pre- 
determined points  and  then  sketching  in  free  hand  a 
curve  passing  through  these  points.  Then  the  irregu- 
lar curve  is  adjusted  to  follow  as  closely  as  possible 
this  free  hand  curve.  By  continually  applying  the 
irregular  curve  to  pass  through  the  points  the  desired 
curve  can  be  secured.  When  using  the  irregular  curve 
the  ruling  pen  must  always  be  held  tangent  to  the  sur- 


10 

face  of  the  eurve  and  be  held  vertical.     Be  careful  not 
to  press  against  the  edge  of  the  curve  hard  enough  to 


PLATE  2 


press  the  blades  of  the  pen  together.     Plate  2  shows 
an  irregular  curve. 

OTHEK  MATERIALS  AND  INSTRUMENTS 
Proportional  Dividers. — These  differ  from  ordinary 
dividers  in  that  they  have  four  points,  two  of  which 
when  set  to  the  full  dimensions  will  be  reproduced  by 
the  other  pair,  but  at  a  different  scale.  In  appearance 
they  are  very  much  like  a  pair  of  double  ended  dividers. 
They  are  provided  with  a  movable  slide  which  can  be 
fastened  when  the  ends  of  the  instrument  are  adjusted 
for  the  desired  reduction.  They  are  generally  used 
for  transferring  distances  from  one  place  to  another 
and  either  reducing  or  enlarging  the  scale  in  the  opera- 
tion. As  the  draftsman  has  to  show  on  the  small  sheet 
of  paper  provided  for  this  work  machines,  etc.,  of  all 


11 

sizes,  it  can  be  readily  seen  that  this  instrument  comes 
in  very  handy,  especially  if  working  from  a  large  model 
or  blue  prints.  Some  dividers  are  marked  for  the 
proportions  and  are  provided  with  a  rack  movement 
for  adjustment  and  with  a  screw  for  holding  in  the 


PLATE  3 


desired  position.  This  instrument  is  rather  expensive 
to  buy  but  the  draftsman  will  usually  find  the  firm  by 
whom  he  is  employed  has  a  pair  for  the  use  of  their 
men.  Plate  3  shows  a  pair  of  proportional  dividers. 

Erasing  Shield, — Used  for  erasing  certain  lines 
without  disturbing  adjacent  lines.  It  is  made  of  a 
thin  piece  of  metal  with  different  size  slots  in  it.  The 
shield  is  placed  on  the  line  to  be  .erased  with  the  slot 
uncovering  the  line.  Then  by  rubbing  the  eraser  in 
the  slot  the  line  is  erased  without  erasing  any  other 
line. 

Croiv  Quill  Pen. — This  is  a  pen  similar  to  an  or- 
dinary writing  pen  but  very  much  finer.  It  is  used  to 
ink  small  parts  which  require  very  fine  and  delicate 
lines,  and  which  cannot  be  made  with  instruments. 

Transfer  Sheet. — A  transfer  sheet  is  a  sheet  of  thin, 
tough  paper  one  side  of  which  is  blackened  with  graph- 
ite. It  is  used  when  it  is  desired  to  make  an  exact  copy 
of  a  drawing,  print,  sketch,  etc. 

To  use,  place  the  transfer  sheet  with  the  graphite 
side  down  against  your  Bristol  board.  On  the  transfer 
sheet  place  the  drawing,  or  whatever  is  to  be  copied, 
in  the  exact  position  desired,  and  fasten  with  thumb 


12 

tacks,  being  sure  to  place  the  tacks  outside  the  cut  out 
lines  of  your  drawing.  Then  with  a  stylus  (described 
later),  or  a  very  hard  pencil,  follow  carefully  the  lines 
of  the  drawing,  and  the  impress  will  make  a  clearr 
clean-cut  copy  on  your  bristol  board.  You  can  easily 
make  your  own  transfer  sheet  by  scraping  or  filing  the 
graphite  from  a  very  soft  pencil  on  one  side  of  a  plain 
white  sheet  of  thin,  tough  paper,  and  then  with  a  soft 
cloth  rubbing  the  graphite  until  the  entire  surface  of 
the  paper  is  a  jet  black.  Be  sure  and  dust  off  all  loose 
particles  so  as  not  to  smear  the  surface  of  the  bristol 
board.  Do  not  use  typewriter  carbon  sheets  for  if  a 
mistake  is  made  it  is  impossible  to  erase  the  marks. 

Stylus. — A  stylus  is  an  instrument  with  a  hard  sharp 
steel  point  which  is  used  in  conjunction  with  a  transfer 
sheet  to  make  exact  copies  of  prints,  etc.  It  is  held  in 
the  hand  the  same  as  a  pencil  or  pen,  and  by  pressing 
the  sharp  steel  point  on  the  lines  of  the  print,  the  copy 
is  made. 

Pencil  Pointer. — A  pencil  pointer  is  used  to  secure 
very  sharp  points  on  the  leads  in  pencils  and  instru- 
ments. It  consists  of  a  piece  of  fine  sandpaper,  or 
emery  cloth,  fastened  to  a  flat  board,  provided  with  a 
handle. 

Burnisher. — A  burnisher  is  used  to  polish  the  sur- 
face of  the  bristol  board  when  it  has  been  made  rough 
by  an  erasure.  It  usually  consists  of  a  steel  or  glass 
rod  which  has  an  end  or  knob  with  a  highly  polished 
surface.  This  is  rubbed  over  the  rough  surface  of  the 
paper  until  a  hard,  smooth  surface  is  secured  by  the 
friction. 

Cleaning  Erasers. — Cleaning  erasers,  for  cleaning 
the  lint,  dirt,  etc.,  from  the  surface  of  the  drawing 
paper,  are  very  convenient  to  have.  The  soft  sponge 
rubber,  or  the  art  gum,  are  the  best  for  this  work. 


CHAPTER  II 

USE  OF  INSTRUMENTS 

Introductory. — The  following  instruments  usually 
come  in  sets  in  a  case  or  box,  and  will  therefore  be  con- 
sidered under  a  separate  chapter.  However,  it  is  not 
necessary  for  a  beginner  to  always  buy  a  case  of  in- 
struments as  some  sets  contain  certain  pieces  that  are 
seldom  if  ever  used,  and  then  sometimes  separate  in- 
struments can  be  bought  of  just  as  good  quality,  but 
much  less  in  price.  If  possible  it  might  be  wise  before 
purchasing  to  secure  the  advice  of  some  draftsman  who 
is  experienced  in  the  use  and  care  of  instruments. 

I  will  describe  the  use  and  construction  of  the  in- 
struments which  I  consider  necessary  for  first-class 
patent  work. 

Ruling  Pen. — The  ruling  pen  is  one  of  the  most  im- 
portant instruments  which  a  draftsman  uses.  On  its 
skillful  use  depends  the  good  looks  of  the  drawing.  It 
is  used  to  draw  straight  lines  along  the  tee-square 
blade,  or  the  edges  of  the  triangle.  It  has  two  steel 
blades  which  are  opened  and  closed  by  an  adjusting 
screw.  These  blades  should  be  tempered  properly,  so 
that  they  will  not  be  soft  and  wear  away  quickly.  Ink 
is  inserted  between  the  blades  by  means  of  a  quill  which 
will  be  found  in  the  ink  bottle.  Never  dip  the  blades 
in  the  ink.  After  filling  the  pen  with  ink  test  it  on 
the  edge  of  your  paper  to  see  if  you  have  the  desired 
width  of  line.  By  regulating  the  distance  between  the 
blades  with  the  adjusting  screw,  a  line  of  any  desired 


14 

thickness  can  be  secured.  Hold  the  pen  in  the  right 
hand  (unless  you  are  left  handed)  with  the  thumb  and 
the  first  and  second  fingers,  with  the  adjusting  screw 
away  from  you,  and  place  the  pen  against  the  tee- 
square  blade  or  triangle  with  its  blades  parallel  to  the 
direction  in  which  you  draw  the  line.  Hold  the  pen 
nearly  perpendicular  to  the  surface  of  the  drawing, 
inclining  very  slightly  in  the  direction  in  which  the 
line  is  to  be  inked.  The  other  fingers  rest  lightly  on 
the  tee-square  or  triangle.  Hold  the  pen  at  the  start- 


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SCREW  DRIVER    \ 
fjsK  FOIKT  roR  COXXTVUSSES 

PLATE  4 


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ing  point  just  an  instant  until  the  ink  begins  to  flow, 
then  move  at  an  even  speed  to  the  right  until  the  de- 
sired length  of  line  is  made.  The  pen  should  be  re- 
moved immediately  on  reaching  the  end  of  the  line, 
otherwise  the  line  is  liable  to  spread.  If  a  number  of 
lines  are  to  meet  at  a  point,  all  lines  should  be  drawn 
from  the  point  and  not  towards  it.  Be  sure  you  do 
not  press  the  blades  of  the  pen  too  hard  against  the 


15 

edge  of  the  tee-square  or  triangle,  as  this  will  cause  an 
uneven  line.  The  pen  should  touch  the  edge  lightly 
and  the  pressure  on  the  pen  should  be  uniform  through- 
out the  length  of  the  line,  otherwise  it  will,  cause  an 
unevenness  of  the  line.  Do  not  lay  away  your  pen 
after  Inking  without  first  thoroughly  cleaning.  A 
good  many  draftsmen  have  two  sizes  of  pens,  a  large 
one  for  the  thick  shade  and  border  lines,  and  a  small 
one  for  fine  shade  lines.  This  is  not  necessary,  how- 
ever, as  a  medium  size  pen  will  answer  all  purposes. 
Plate  4  shows  a  set  with  two  pens. 

Compass. — The  compass  is  used  to  draw  circles  or 
parts  of  circles  with  either  pencil  or  ink.  It  has  a 
fixed  leg  with  a  needle  point,  used  as  a  centre  around 
which  the  circle  is  drawn,  and  another  leg  with  re- 
movable pencil  and  pen  points.  The  legs  are  jointed 
so  that  the  points  can  be  made  perpendicular  to  the 
paper  when  large  circles  are  drawn.  For  circles  larger 
than  can  be  conveniently  made  with  the  compass  the 
draftsman  should  use  the  extension  bar  which  is  always 
furnished.  This  bar  extends  the  pencil  or  pen  points 
so  that  circles  of  considerable  radii  can  be  made.  The 
two  legs  of  the  compass  are  joined  in  what  is  called  the 
head  of  the  compass.  This  head  should  be  well  con- 
sidered when  buying  this  instrument.  It  should  be 
constructed  so  that  the  legs  are  held  firmly  in  any  posi- 
tion, but  not  so  tight  that  they  cannot  be  readily  ad- 
justed. The  heads  of  some  compasses  are  fitted  with 
small  slots  into  which  fits  a  key  for  tightening  the  same. 
Others  are  held  firmly  with  a  small  set  screw  which 
can  be  tightened  with  the  screw  driver,  which  is  always 
furnished  with  the  sets  of  instruments.  The  pencil 
leg  of  the  compass  should  have  hard  lead,  sharpened 
to  a  conical  point.  For  ink  work  remove  the  pencil 
leg  by  loosening  the  little  set  screw  and  insert  the  pen 


16 

leg.  The  pen  point  of  the  pen  leg  is  adjusted  for 
thickness  of  lines  the  same  as  the  ruling  pen.  Always 
insert  the  ink  between  the  blades  with  the  quill  as  pre- 
viously described.  The  needle  point  in  the  fixed  leg 
is  always  a  separate  piece  of  steel,  held  in  a  socket  in 
the  end  of  the  leg  by  a  small  set  screw.  This  steel 
piece  has  a  square  shoulder  below  which  projects  a 
very  fine  needle  like  point. 

To  open  the  compasses  to  a  desired  radius,  hold  with 
the  needle  point  leg  resting  between  thumb  and  fourth 
finger,  and  the  other  leg  between  the  two  middle  fingers. 

To  scribe  a  circle  or  arc,  hold  the  compasses  lightly 
at  the  top,  between  the  thumb,  first  and  second  fingers, 
and  rotate  from  right  to  left.  Always  press  lightly  on 
the  needle  point,  just  enough  to  keep  it  from  slipping. 
Be  careful  not  to  dig  a  hole  in  the  paper. 

Only  one  hand  should  be  used  to  operate  the  com- 
passes. The  beginner  has  a  great  tendency  to  use  both 
hands,  which  makes  him  appear  awkward  and  gives  a 
bad  impression  although  he  may  be  a  good  workman. 
The  only  exception  is  when  the  extension  bar  is  used, 
then  it  is  absolutely  necessary  to  use  both  hands  to 
hold  the  point  perfectly  steady. 

One  style  of  compass  with  pencil  point  adjusted  is 
shown  on  Plate  4,  also  the  pen  point  and  lengthening 
bar  used  with  the  same. 

Dividers. — This  instrument  is  used  to  transfer  dis- 
tances or  spaces  from  one  drawing  to  another  or  from 
one  part  of  a  drawing  to  another.  Also  used  for  di- 
viding circles,  arcs  and  lines  into  equal  parts.  It  is 
simliar  in  design  to  the  compass,  but  the  legs  are  fixed. 
There  are  no  joints  and  both  legs  have  long  tapered 
points  very  sharp,  so  as  not  to  punch  large  holes  in  the 
paper.  It  should  be  held  while  using  the  same  as  the 
compass,  but  when  spacing  turn  the  instrument  alter- 


17 

nately  from  right  to  left.     See  Plate  4  for  the  style  of 
dividers  most  commonly  used. 

Bow-Dividers. — This  instrument  is  used  for  the 
same  purpose  as  dividers,  but  is  much  more  convenient 
and  accurate  for  small  work.  It  has  an  adjusting 
screw  which  will  allow  for  very  fine  adjustment.  Some 
of  these  instruments  are  constructed  with  a  single 
threaded  piece  fastened  to  one  leg  and  adjusted  by  a 
screw  on  the  outside  of  the  other  leg.  This  type  is 
shown  on  Plate  4.  Others  are  fitted  with  a  piece  with 
both  right  and  left-hand  threads  which  moves  the  legs 
of  the  instrument  by  turning  a  central  thumb  screw. 
This  latter  type  is  used  more  for  the  reason  that  it  can 
be  easily  adjusted  with  one  hand.  When  spacing  the 
instrument  is  held  in  the  hand  the  same  as  the  large 
dividers  and  also  used  in  the  same  manner. 

Bow-Pencil. — A  bow-pencil  is  a  pencil  compass  for 
making  small  circles  and  arcs  and  should  be  used  for 
all  small  work  in  preference  to  compasses.  The  pencil 
point  should  be  fitted  with  hard  lead  sharpened  to  a 
conical  point.  The  means  of  adjustment  is  the  same 
as  the  bow-dividers. 

Bow-Pen. — This  instrument  is  used  to  ink  all  circles 
and  arcs  penciled  with  the  bow-pencil.  It  is  con- 
structed the  same  as  the  bow-pencil  except  that  it  has 
a  pen  instead  of  a  pencil  point.  Do  not  ink  circles 
with  this  pen  which  require  the  pen  to  be  opened  to 
such  an  extent  as  to  cause  the  point  to  make  a  ragged 
line.  Always  use  large  compasses  for  circles  over  one 
inch  or  one  inch  and  one-quarter  radius.  Ink  is  in- 
serted in  pen  point,  and  the  desired  thickness  of  a  line 
is  secured  in  the  same  manner  as  described  under 
ruling  pen. 


CHAPTER  III 
PENCILING  THE  DKAWING 

A  drawing  poorly  penciled  is  seldom  well  inked. 
Therefore,  the  beginner  should  be  very  particular 
about  his  pencil  work  and  before  he  starts  should  be 
sure  his  pencil  has  a  sharp,  conical  point  and  that  the 
leads  in  his  other  instruments  are  also  well  sharpened. 
Care  should  be  taken  to  keep  them  in  this  condition 
as  this  is  a  very  important  requisite  in  the  execution 
of  this  part  of  the  work.  As  the  point  wears  away  it 
should  be  touched  up  frequently  on  a  piece  of  emery 
cloth  or  sandpaper. 

When  drawing  a  line  the  pencil  should  always  be 
held  vertical,  or  nearly  so,  and  should  be  pressed  very 
lightly  on  the  paper,  making  the  lines  as  fine  as  is  con- 
sistent with  clearness.  If  the  pencil  is  inclined  at  all 
it  should  be  in  the  direction  in  which  it  is  moved. 

With  the  pencil  and  instruments  in  perfect  working 
order,  the  next  important  step  is  to  place  the  drawing 
paper  on  the  board  and  fasten  it  so  that  the  edges  are 
parallel  to  the  edges  of  the  board.  First  lay  the  bristol 
board  flat  on  the  board ;  put  on  the  tee-square  with  the 
head  at  the  left-hand  side  of  the  board ;  then  slide  tee- 
square  up  nearly  to  the  top  and  arrange  the  paper  level 
with  the  blade ;  with  the  right  hand  hold  the  paper  still, 
sliding  the  tee-square  down  a  little,  and  then  pin  the 
top  of  the  paper  with  thumb  tacks  about  1/4"  from  each 
corner.  Next,  pin  the  lower  corners,  being  sure  to 
smooth  the  paper  out  perfectly  flat. 


19 

Now,  the  border  lines  and  cutting  out  lines  should 
be  laid  out  accurately  with  the  scale,  to  the  dimensions 
given  on  Plate  5.  The  draftsman  should  be  very  par- 
ticular to  get  these  dimensions  exact,  as  the  Patent 
Office  will  refuse  to  accept  drawings  unless  they  are 
the  size  here  specified. 

The  cutting  out  lines,  that  is,  the  outside  lines  A, 
B,  C,  D,  where  the  drawing  is  cut  out  when  finished 
must  be  10"  x  15". 

The  border  lines  a,  b,  c,  d,  within  which  all  drawing 
must  be  made  is  8"  x  13".  This  leaves  an  inch  margin 
all  around. 

The  shorter  side  of  the  drawing  is  considered  the 
top,  that  is,  side  "A,"  "B." 

A  light  pencil  line  e.  f.  (don't  ink)  should  be  drawn 
IW  below  the  line  a,  b.  In  this  space,  a-b-e-f,  no 
marks  of  any  kind  should  be  made.  This  space  is 
reserved  for  putting  in  title,  etc.,  at  the  Patent  Office 
in  Washington. 

In  the  lower  right-hand  corner  should  be  penciled 
the  words  "Inventor,"  "By"  and  "His  Attorney,"  as 
shown  in  Plate  5.  The  inventor's  name,  if  known,  can 
also  be  printed  just  below  the  word  "Inventor." 
There  is  no  fixed  rule  as  to  the  distance  from  lower 
edge  to  place  the  printed  words,  but  enough  space 
should  be  allowed  between  the  inventor's  name  and 
the  words  "His  Attorney"  so  that  the  attorneys  will 
be  able  to  sign  their  names.  About  1%"  usually  is 
allowed. 

There  is  also  no  fixed  rule  as  to  the  style  or  size  of 
the  lettering  to  be  used.  However,  it  is  preferable  to 
always  use. the  same,  size  and  style. 

The  sheet  of  bristol  board  is  now  in  shape  to  start 
penciling  the  drawing.  Before  making  a  line,  how- 
ever, the  draftsman  should  thoroughly  study  the  model, 
sketches,  prints  or  whatever  information  has  been 


20 

given  him  from  which  to  make  his  drawings.  He 
should  be  sure  he  thoroughly  understands  the  inven- 
tion, and  then  decide  on  the  different  views  which  he 
thinks  will  be  necessary  to  fully  illustrate  the  same. 
There  is  always  a  choice  of  views  and  those  should  be 
made  which  convey  the  greatest  amount  of  informa- 
tion, consistent  with  clearness.  Generally  three  views 
of  an  object  are  all  that  are  necessary  to  show  its  form 
and  its  use.  If,  however,  its  construction  is  compli- 
cated, it  may  require  sectional  views,  detail  views,  or 
even  perspective  views  in  addition  to  the  general  views. 
The  draftsman  should  imagine  himself  reading  the 
drawings  and  then  decide  on  how  many  views  are  nec- 
essary to  give  complete  information  in  a  clear  and  con- 
cise manner.  The  draftsman  must  keep  in  mind  that 
he  must  show  clearly  every  feature  of  the  invention 
which  the  inventor  wishes  to  protect  with  his  patent. 

When  the  invention  is  an  improvement  on  some  old 
machine,  the  drawing  must  show  in  one  view,  at  least, 
so  much  of  the  old  structure  as  will  suffice  to  show  the 
connection  of  the  invention  therewith.  Then  also  must 
be  shown  separate  views  of  the  device  detached  from 
the  old  structure. 

After  deciding  on  the  views  to  be  shown  the  drafts- 
man should  make  a  study  as  to  how  the  different  views 
should  be  arranged,  and  how  many  sheets  of  drawings 
will  be  necessary.  The  views  should  of  course  be  ar- 
ranged systematically  on  the  sheet  in  order  that  the 
space  may  be  used  to  the  best  advantage,  and  the  draw- 
ing as  a  whole  will  present  a  pleasing  appearance. 

The  scale  to  which  the  drawing  will  have  to  be  drawn 
will  have  to  be  given  considerable  thought,  as  the  Pat- 
ent Office  does  not  want  any  more  sheets  used  than  is 
absolutely  necessary,  yet,  on  the  other  hand,  it  must  be 
large  enough  so  as  not  to  have  the  mechanism  crowded, 


21 

or  to  have  it  drawn  to  such  a  small  scale  as  not  to  be 
easily  read. 

The  three  views  that  will  fully  illustrate  most  de- 
vices, unless  of  course  they  are  of  a  complicated  mech- 
anism, some  parts  of  which  are  invisible,  are  plan  view, 
front  view,  and  side  view. 

The  drawing  which  represents  the  object  as  if  it 
were  resting  on  a  horizontal  plane  and  the  observer 
looking  at  it  from  directly  above,  is  called  a  plan  or 
top  view. 

A  front  view  (or  front  elevation)  is  drawn  so  that 
it  represents  a  view  with  the  observer  looking  directly 
at  the  front  of  the  object. 

The  side  view  or  side  elevation  shows  the  observer's 
line  of  vision  the  same  as  in  front  view,  but  the  object 
is  shown  as  if  revolved  on  its  axes  90°  either  to  right 
or  left. 

Having  decided  on  the  views  desired  on  the  sheet 
and  calculated  as  accurately  as  possible  the  amount  of 
space  each  view  will  require,  and  the  exact  place  it 
should  be  located  on  the  sheet,  you  can  now  proceed 
to  pencil  the  views. 

As  most  views  centre  around  certain  points,  it  is 
best  to  begin  by  locating  these  points  and  drawing 
through  them  centre  lines  both  vertical  and  horizontal, 
carefully  locating  all  your  distances  thereafter  from 
these  lines. 

It  is  best  usually  to  pencil  the  front  elevation  first, 
but,  of  course,  if  it  is  possible  by  projection  to  work 
on  more  than  one  view,  do  so,  as  much  time  is  saved 
in  this  way. 

After  the  general  views  are  made  you  can  then  pro- 
ceed with  the  detail  and  sectional  views  if  such  are 
necessary.  If  a  sectional  view  is  made  always,  if  pos- 


F 


s 


(I) 


PLAT 


24 

sible,  show  where  the  section  is  taken  with  a  broken 
line  as  at  X-X  in  Fig.  1,  Plate  5. 

Perspective  views  are  used  by  some  draftsmen  for 
showing  up  certain  objects,  but  this  should  never  be 
attempted  by  a  beginner  unless  it  is  some  simple  part 
as  it  requires  a  great  deal  of  study  and  the  draftsman 
must  practice  for  a  long  time.  As  this  book  is  written 
with  the  idea  of  giving  the  beginner  sufficient  knowl- 
edge to  work  in  drafting  in  a  short  time,  I  will  not  take 
up  the  subject  of  perspective  as  I  consider  this  a  subject 
in  itself.  However,  I  advise  the  beginner  after  master- 
ing the  general  rules  and  securing  work  in  drafting  to 
get  a  good  book  on  perspective  and  study  the  subject. 

Sometimes  shafts  and  other  long  and  slender  parts 
wrould  extend  beyond  the  border  line  of  the  drawing  if 
drawn  to  the  proper  scale ;  therefore,  it  is  permissible 
to  break  away  as  shown  at  shaft  (1)  in  Fig.  (3),  Plate 
5.  It  is  understood  that  the  part  broken  away  is  the 
same  shape  and  size  as  the  part  shown. 


CHAPTER  IV 
INKING  THE  DBA  WING 

Never  begin  inking  a  drawing  until  it  has  been  com- 
pletely finished  in  pencil. 

Thoroughly  clean  the  drawing  before  inking,  care- 
fully removing  all  dust,  lint,  etc.,  and  see  that  no  greasy 
or  oily  spots,  or  finger  marks  are  on  the  surface  of  the 
paper.  The  best  way  to  clean  the  drawing  is  to  go 
over  it  lightly  with  a  piece  of  art  gum  and  then  brush 
off  with  a  soft  cloth. 

Shake  the  bottle  of  ink  well  before  you  start  to  ink 
the  drawing.  When  the  bottle  stands  undisturbed  for 
some  time  the  heavy  part  of  the  ink  gradually  settles 
in  the  bottom  and  the  coloring  of  the  lines  will  there- 
fore vary. 

After  filling  an  instrument  with  ink,  try  it  on  the 
border  of  the  bristol  board  outside  of  the  cutting  out 
lines,  and  see  that  your  ink  will  flow  properly  and  that 
you  have  the  right  thickness  of  line.  * 

Before  inking  a  line  think  what  kind  of  a  line  it  is, 
that  is,  whether  light,  medium,  or  heavy,  and  then 
gauge  the  distance  between  the  nibs  accordingly. 

Start  inking  at  the  top  and  left-hand  side  of  the 
drawing  and  work  down  and  towards  the  right,  and 
in  this  way  the  ink  is  not  smeared  by  triangle,  tee- 
square,  or  hands. 

Be  sure  the  pens  are  perfectly  clean,  and  when  filling 
the  same  with  ink  care  should  be  used  not  to  overload. 
Too  much  ink  in  the  pen  will  make  the  line  heavier 
than  desired  and  is  liable  to  cause  blots,  and  too  little 
ink,  on  the  other  hand,  is  liable  to  make  a  gray  or 
streaked  line. 


26 

Care  should  also  be  taken  not  to  allow  ink  to  get  on 
the  outside  of  the  blades,  as  it  is  then  apt  to  cause  a 
blot  as  you  draw  the  pen  along  the  edge  of  the  tee- 
square  or  triangle. 

Be  particular  not  to  get  lint  or  fuzz  in  the  pen  points 
as  it  will  make  a  smear  line. 

If  a  number  of  lines  radiate  from  a  point  be  sure 
and  allow  sufficient  time  for  each  line  to  dry,  otherwise 
it  is  very  liable  to  blot. 

The  best  results  will  be  obtained  by  inking  in  the 
following  sequence: 

1st.  Ink  all  large  circles  and  arcs  with  the  compass, 
beginning  at  the  top  of  the  sheet. 

2nd.  Ink  all  small  circles  and  arcs  with  the  bow- 
pen,  beginning  with  the  uppermost.  Be  sure  and 
shade  all  the  circles  as  you  go  along. 

3rd.  Draw  all  horizontal  lines  with  the  ruling  pen 
and  tee-square,  starting  at  the  top  and  left-hand  side 
of  sheet.  Be  sure  the  flat  side  of  the  pen  is  laid  against 
the  tee-square  with  the  adjustable  nut  away  from  the 
edge.  The  taper  of  the  blade  is  sufficient  to  throw  the 
point  enough  so  that  if  the  pen  is  held  vertical,  or 
nearly  so,  there  will  be  no  blotting. 

Hold  pen  at  starting  point  for  just  an  instant  until 
ink  begins  to  flow,  then  move  with  moderate  speed  to- 
wards the  right  along  the  edge  of  the  tee-square.  On 
reaching  end  of  line  pen  should  be  immediately  lifted 
to  prevent  the  ink  from  spreading. 

It  is  easier  to  draw  a  straight  line  up  to  a  curve  than 
to  take  a  curve  up  to  a  line.  That  is  the  reason  why  all 
curves  and  arcs  should  be  inked  before  the  straight 
lines. 

4th.  After  inking  all  horizontal  lines  the  next  in 
order  are  all  vertical  lines.  They  are  usually  drawn 
against  the  edge  of  the  triangle,  but  the  tee-square  can 
be  used  if  desired ;  if  using  triangle  for  guiding  surface 


27 

always  begin  at  the  left-hand  side  of  the  drawing  and 
work  over  to  the  right,  thus  avoiding  the  chances  of 
blotting. 

5th.  Draw  with  the  triangles  and  tee-square  all  30°, 
60°  and  45°  lines,  except  those  for  cross  sections.  All 
cross  sectional  lines  should  be  made  after  the  outline 
of  the  drawing  has  been  completed. 

6th.  Ink  the  other  oblique  lines  which  happen  to  be 
in  the  drawing.  Use  triangle  for  ruling  surface  as  it 
is  the  most  convenient  to  handle  and  being  of  trans- 
parent material  is  the  easiest  to  adjust  to  the  lines. 

7th.  Ink  all  curved  surfaces  which  could  not  be 
made  with  the  compass  or  bow-pen.  For  these  lines 
use  the  irregular  curve.  Be  sure  to  hold  the  ruling 
pen  vertical,  that  is,  don't  have  it  slanting  towards  or 
away  from  the  edge  of  the  curve.  If  you  do  you  are 
liable  to  blot  or  cause  a  ragged  line. 

8th.  Make  all  small  connections,  fillets,  etc.,  and  all 
irregular  or  broken  lines.  Use  the  crow-quill  or  free- 
hand pen  for  this  work. 

9th.  Ink  all  cross  section  lines,  making  sure  all  ad- 
joining parts  are  sectioned  in  opposite  directions.  Be 
sure  and  make  these  lines  finer  than  the  outline. 

10th.  Shade  all  concave  and  convex  surfaces  if  doing 
so  will  add  to  a  clearer  understanding  of  the  invention. 

Be  sure  and  consider  your  drawing  before  starting 
any  shading.  You  must  remember  if  you  shade  some 
curved  surfaces  you  must  shade  all  curved  surfaces. 

llth.  Shade  whatever  other  surfaces  you  consider 
necessary. 

12th.  Ink  in  the  "Inventor,"  etc.,  which  is  penciled 
in  lower  right-hand  corner. 

13th.  Ink  in  the  border  lines.  The  line  on  the  right 
side  and  at  bottom  should  be  at  least  twice  as  heavy  as 
the  other  two  sides.  See  Plate  5. 

Carefully  look  over  your  drawing  to  see  you  have 
not  missed  anything. 


CHAPTER  V 

SECTIONS  AND  SECTION  LINING 

Sections. — Sometimes  it  is  necessary  to  show  the 
inner  construction  of  an  object  and  to  show  it  clearly. 
Dotted  lines  are  often  used  to  show  these  invisible 
parts,  but  this  often  makes  the  drawing  appear  com- 
plicated, and  makes  it  hard  to  read.  To  eliminate  this 
confusion  of  lines  an  object  is  often  represented  as 
though  it  had  been  cut  by  a  plane,  all  parts  between 
this  plane  and  the  observer  being  considered  as  re- 
moved. This  is  called  a  section  or  a  sectional  view. 
Figs.  2  and  3  on  Plate  5  are  sectional  views.  If  pos- 
sible to  show  just  where  this  cutting  plane  passes 
through  the  object,  long  broken  lines  are  used.  This 
is  shown  at  X-X  in  Fig.  1,  Plate  5,  which  shows  where 
the  section  shown  in  Fig.  3  is  taken. 

If  the  section  is  taken  in  the  direction  of  the  length 
of  the  object  it  is  called  a  longitudinal  section. 

If  the  section  is  taken  perpendicular  to  the  longi- 
tudinal, that  is,  at  right  angle  to  the  length  of  the 
object,  it  is  called  a  vertical  section.  Fig.  2,  Plate  5, 
is  a  vertical  section. 

When  only  a  small  portion  of  a  view  is  removed  to 
show  some  special  part,  it  is  called  a  detail  section. 

Section  Lining. — The  solid  surfaces  cut  by  the  sec- 
tion plane  are  shown  by  what  is  known  as  section  lining 
or  cross  hatching.  This  is  shown  by  drawing  a  series 
of  equidistant  lines  on  the  exposed  area.  These  sec- 
tion lines  should  be  drawn  at  45°  angle  to  the  horizontal 


SECTION  DF  MATERIALS. 


Wood  or  Metal.     Glass  or  Porcelain.  Refractory  Material 


Cenoent. 


Insulation. 


Carbon 


Cork.          Fibrous  Material.        Liquid. 


Fabrics. 
Coarse  Fine 


Color    Chart. 


Blue     Greeo   Yellow    Black     Purple  Orar)&e 


PLATE  6 


30 

when  possible,  about  1/16"  to  1/20"  apart,  unless  it  is 
a  very  small  area.  The  beginner  is  very  liable  to  space 
his  lines  too  close  and  should  be  very  careful  to  avoid 
this  error.  He  should  keep  in  mind  that  the  drawing 
is  to  be  reduced  later  and  if  too  close  sectioning  is 
made,  it  is  liable  to  give  a  solid  effect. 

Section  lining  by  the  eye  requires  considerable  prac- 
tice, as  it  is  difficult  to  keep  the  lines  equally  spaced. 
After  drawing  six  or  eight  lines  of  sectioning  it  is  a 
good  idea  to  glance  back  over  the  completed  area  and 
correct  any  variation  in  the  spacing.  By  continually 
watching  the  lines  of  the  completed  portion  you  can 
judge  whether  to  widen  or  narrow  the  spaces,  and  with 
practice  will  be  able  to  get  them  uniform  throughout. 

Adjacent  areas  should  be  sectioned  in  opposite  direc- 
tions in  order  to  more  clearly  define  the  limits  of  the 
parts.  See  parts  (2)  and  (3),  Plate. 5.  In  case  there 
are  three  or  more  areas  adjoining  the  draftsman  can 
draw  the  section  lines  at  60°  and  30°  angles  instead 
of  the  usual  45°  angle. 

The  section  lines  should  be  considerably  lighter  in 
weight  than  the  lines  used  in  the  outline. 

It  is  not  necessary  to  cross  section  bolts,  shafts  and 
cylindrical  solids  even  though  they  are  cut  by  the  sec- 
tion. This  is  shown  in  Fig.  3  where  the  section  is 
taken  at  X-X  in  Fig.  1,  through  centre  of  shaft  (1), 
but  the  shaft  is  not  shown  cut.  For  representing  dif- 
ferent materials  in  section  a  standard  chart  is  shown 
on  Plate  6.  Also  a  color  chart,  and  the  proper  way  to 
make  fabrics  is  shown  on  the  same  plate. 


CHAPTER  VI 
OUTLINE  SHADING 

Outline  shading  is  always  required  in  patent  draw- 
ings and  therefore  the  beginner  should  pay  particular 
attention  to  the  few  rules  which  govern  the  same. 

The  shade  lines  are  used  to  make  a  drawing  less  diffi- 
cult to  read,  and  add  greatly  to  the  clearness  of  the 
views  by  indicating  the  relation  of  the  surfaces  to  one 
another,  that  is,  they  show  whether  the  part  looked  at 
is  above  or  below  the  plane  of  the  surface. 

On  Plate  7,  Fig.  4,  let  1-2-3-4  represent  the  plane  of 
a  surface.  Then  by  the  shade  lines  it  is  easy  to  tell 
that  5  is  above  the  plane  while  6  is  below.  Just  by 
glancing  at  the  figure  you  can  readily  see  that  5  is  a 
square  boss  while  6  is  a  square  hole.  Without  the 
shade  lines  it  would  be  necessary  to  draw  another  view 
of  the  object  to  show  this. 

The  light  is  always  assumed  to  come  from  the  upper 
left-hand  corner  of  the  drawing  and  to  move  downward 
and  to  the  right  at  an  angle  of  45°,  always  moving  in 
parallel  lines  as  indicated  by  arrow  lines  in  Fig.  4. 

The  surfaces  touched  by  these  lines,  representing  the 
direction  of  light  rays,  are  always  light  lines,  while 
the  lines  not  in  the  light  are  always  heavier  or  black 
lines. 

All  views  of  an  object  are  to  be  considered  as  top 
views  and  equally  exposed  to  light  throughout  their 
entire  surface,  that  is,  all  figures  whether  bounded  by 
straight  or  curved  lines  have  heavier  shade  lines  on 
those  sides  which  cannot  be  touched  by  parallel  lines 


32 

drawn  at  45°  angle  irrespective  of  their  location  on  the 
sheet.  Therefore,  you  can  always  use  shade  lines  on 
the  right  hand  and  lower  edges  of  all  surfaces  above 
the  plane.  Below  the  plane  is  just  the  reverse. 

Shade  lines  should  be  about  two  or  three  times  the 
thickness  of  the  ordinary  outline.  There  is  no  fixed 
rule  for  this  and  much  depends  on  the  drawing.  In 
some  cases  if  the  lines  were  inked  as  heavy  as  this  they 
would  merge  into  other  lines,  or  in  case  the  views  shown 
were  very  small  it  would  make  them  appear  clumsy. 

In  shading  straight  lines  the  extra  thickness  of  the 
line  is  usually  added  to  the  outside  of  the  line.  This 
is  done  generally  by  placing  the  edge  of  the  tee-square 
or  triangle  slightly  below  the  line  to  be  shaded,  then 
the  pen  is  opened  a  trifle  wider  and  a  line  is  ruled  par- 
allel to  the  same.  The  handle  of  the  pen  is  then 
slightly  inclined  towards  the  draftsman  and  by  draw- 
ing a  line  in  this  position,  the  space  between  the  two 
lines  will  be  filled.  For  most  shading  of  straight  lines, 
however,  the  pen  can  be  set  wider  and ,  the  shade  line 
ruled  so  close  to  the  outline  as  to  make  it  blend  all  into 
one  thick  line.  Some  draftsmen,  when  inking  the 
shade  lines,  simply  widen  the  nibs  of  the  pen  to  the 
desired  thickness  and  draw  the  one  line. 

To  shade  a  circle,  first  ink  the  circle  with  a  light  line. 
Then  with  the  same  radius  and  a  centre  located  slightly 
eccentric  and  on  a  45°  angle  with  the  centre,  draw  an- 
other semi-circle,  adding  thickness  to  one  side  or  the 
other,  depending  upon  whether  it  is  above  or  below 
the  plane  of  the  surface.  Above  the  plane  is  shown  at 
8,  in  Fig.  4,  Plate  7.  Below  the  plane  is  shown  at  7. 

For  all  concentric  circles  the  same  eccentric  centre 
is  used  for  shading.  This  is  shown  at  7  where  a  rep- 
resents the  concentric  centre  and  a'  the  eccentric 
centre. 


SHADE  JLINE5 


\ 


\ 


SURFACE  SHADING 


PLATE  7 


CHAPTER  VII 
SURFACE  SHADING 

Shading  of  the  surfaces  of  objects  is  not  required 
by  the  Patent  Office,  but  it  is  desired  in  a  great  many 
cases  in  which  its  use  makes  the  reading  of  the  draw- 
ing much  easier.  All  patent  draftsmen  are  called  upon 
some  time  to  use  shading;  therefore,  it  is  a  good  idea 
for  all  beginners  to  learn  how  to  shade,  and  then  to 
practice  considerably,  as  it  requires  extensive  practice 
and  extreme  care  in  order  to  obtain  pleasing  results. 

Concave  and  convex  surfaces  are  almost  always 
shaded  and  are  shown  by  drawing  parallel  lines.  On 
large  convex  surfaces  the  heavy  and  light  parts  of  the 
surface  are  often  found  by  drawing  a  semi-circle  the 
diameter  of  the  cylinder  and  then  drawing  a  line  at  an 
angle  of  about  20°  to  the  vertical  centre  line  and  pro- 
jecting to  the  cylinder  surface.  The  point  where  it 
touches  will  represent  where  the  surface  is  most  bril- 
liantly lighted  and  therefore  where  there  should  be  no 
shading.  In  the  same  way  the  darkest  part  of  the 
surface  can  be  found  by  projecting  from  a  line  drawn 
at  45°  to  the  centre  as  shown  clearly  in  Fig.  5,  Plate  7. 

Medium  convex  surfaces  shown  by  Fig.  6  are  more 
generally  shaded  by  starting  from  the  edges  and  grad- 
ually decreasing  the  thickness  of  the  lines  and  at  the 
same  time  increasing  the  space  between  the  lines  as 
they  approach  the  centre. 

The  lines  on  the  shaded  side  of  the  surface  are  of 
course  made  heavier  than  the  other  side. 

Small  convex  surfaces  as  in  Fig.  7  are  always  shaded 
on  the  heavy  side  only. 


35 

In  shading  concave  surfaces,  see  (12),  Plate  5,  the 
operation  is  just  reverse,  that  is,  the  darkest  surface 
is  opposite  side  to  that  shown  in  convex. 

Large  spheres  are  usually  shaded  by  drawing  con- 
centric circles  and  arcs,  the  point  of  brilliancy,  that  is, 
the  point  where  no  shading  is  shown,  being  considered 
at  a  point  about  two-thirds  distance  from  the  upper 
edge  to  the  centre  on  a  line  drawn  at  45°  with  the  centre 
and  upwards  to  the  left. 

The  darkest  part  is  about  one-third  distance  from 
lower  edge  to  the  centre  on  the  same  45°  line.  See 
Fig.  8. 

Most  spheres,  however,  are  usually  shaded  with  the 
heaviest  lines  at  the  edges  and  gradually  decreasing 
the  thickness  and  increasing  the  space  between  the 
lines.  As  the  centre  is  approached  the  arcs  are  also 
gradually  shortened  as  can  be  readily  seen  in  Fig.  9. 
Sometimes  small  spheres  are  shaded  on  the  one  side 
only  as  in  Fig.  1,  Plate  5. 

Flat  surfaces  are  shaded  by  spacing  lines  an  equal 
distance  apart.  This  produces  what  is  called  a  flat 
shade.  This  shading  is  used  when  several  surfaces  in 
different  planes  lie  so  close  that  it  is  not  easy  to  dis- 
tinguish their  location.  This  is  shown  in  Fig.  10, 

Inclined  surfaces,  as  in  Fig.  11,  are  usually  shaded 
by  parallel  lines  evenly  spaced,  the  thickness  of  the 
lines  being  gradually  reduced  as  the  bottom  of  the 
incline  is  approached.  The  greater  the  angle  of  in- 
clination the  closer  the  spacing  of  the  lines  should  be. 

Surface  shading  should  be  used  very  sparingly  and 
should  not  be  used  at  all  unless  the  draftsman  is  sure 
it  will  add  clearness  to  the  drawing  by  making  it  much 
easier  to  read  and  understand. 

The  Patent  Office  does  not  require  surface  shading 
nor  does  it  encourage  its  use  except  for  such  cases 
where  the  drawing  cannot  be  readily  understood  with- 
out its  use. 


CHAPTER  VIII 

LETTERING  THE  DRAWING 

In  filing  patent  applications,  a  description  of  the 
drawing  is  always  required.  This  is  usually  written 
by  an  attorney,  and  the  description  will  refer  to  the 
different  views  by  figures  and  to  the  different  parts  by 
letters  or  numerals.  The  different  figures  should  be 
consecutively  numbered,  and  the  different  parts,  when 
they  appear  in  more  than  one  view  of  the  drawings, 
should  always  have  the  same  reference  letter. 

The  attorney  will  usually  place  the  numerals  or  let- 
ters on  the  drawing  with  pencil  and  the  draftsman  will 
be  required  to  put  them  neatly  iix  ink  and  connect  to 
the  parts  to  which  they  refer  with  short  broken  or 
wiggley  lines,  as  shown  on  Plate  5. 

They  should  not  be  placed  on  shaded  or  sectioned 
surfaces,  and  when  it  is  difficult  to  avoid  this  a  blank 
space  must  be  left  in  the  shading  or  sectioning  so  the 
number  will  stand  out  clearly  as  shown  at  1  in  Fig.  2 
of  Plate  5. 

No  fixed  style  or  size  of  lettering  is  required,  but  the 
Patent  Office  does  distinctly  specify  that  all  letters  and 
figures  must  be  carefully  formed.  They  also  require 
that  the  letters  and  figures  should  be  at  least  %"  high. 
If  there  is  sufficient  room  so  that  the  letters  will  not 
appear  crowded  they  should  be  made  larger,  as  the 
drawing  is  reduced  to  about  6"  x  9%"  when  the  patent 
is  issued,  and  if  made  too  small  the  letters  will  be  in- 
distinct. 


CHAPTER  IX 
SKETCHING 

It  is  very  important  that  a  patent  draftsman  should 
be  able  to  sketch  at  sight  different  objects  or  things  he 
may  see,  such  as  bolts,  shafts,  pieces  of  machinery,  etc. 
It  very  often  happens  a  patent  drawing  is  required  of 
some  piece  of  mechanism  which  is  so  located  that  it  is 
impossible  to  work  with  drawing  instruments  and  it  is 
then  necessary  to  make  sketches  of  the  parts.  These 
free-hand  drawings  should  be  so  clear  that  on  the  re- 
turn of  the  draftsman  to  his  office,  or  even  at  some 
later  date,  he  will  be  able  to  make  a  patent  drawing 
which  will  show  clearly  and  concisely  the  mechanism. 

To  sketch  rapidly  and  clearly  requires  practice  and 
only  with  practice  can  anything  in  this  line  of  work 
be  accomplished. 

It  also  requires  a  thorough  training  in  observation, 
which  in  itself  is  one  of  the  best  educational  processes. 

It  is  very  necessary  to  train  the  eyes  to  proportion. 
It  is  sometimes  impossible  to  take  any  measure- 
ments, and  it  is  then  necessary  to  assume  the  size  of  a 
certain  part  and  then  compare  the  other  parts  to  be 
drawn  with  this  part.  The  scale  is  unimportant,  but 
proportions  should  be  secured  as  nearly  as  possible. 

Perspective  or  isometric  views  are  often  useful  as  a 
substitute  for  many  views,  but  if  unfamiliar  with  this 
method,  the  orthographic  representation  will  suffice  for 
all  cases. 


38 

First  find  that  part  of  the  mechanism  which  is  new 
and  sketch  each  detail  making  it  complete  in  itself. 
Then  make  a  general  outline  of  the  whole  device. 

Sketch  centre  lines,  and  proportion  with  the  eye  the 
distances  of  the  parts  from  these  centres. 

Sectioned  lined  paper  is  good  to  use  in  this  work. 

Pencil  should  be  H  or  HH  grade.  Never  use  a  hard 
pencil. 

Draw  the  lines  lightly  at  first  and  correct  any  por- 
tion necessary,  then  when  considered  right  make  the 
lines  heavy. 


CHAPTER  X 

CARE  OF  INSTRUMENTS 

The  drawing  instruments  are  of  such  a  delicate  con- 
struction that,  unless  good  care  is  taken  of  them,  they 
will  become  worn  or  broken  and  will  not  work  prop- 
erly. After  using  an  instrument  it  should  be  wiped 
clean  and  laid  away  in  the  case.  It  should  never  be 
thrown  down  carelessly  on  the  desk  or  into  a  drawer 
as  the  points  are  liable  to  be  damaged. 

About  every  two  or  three  months  the  threads  on  all 
small  screws  should  be  oiled.  If  this  is  not  done  the 
threads  will  soon  become  badly  worn  or  stripped  and 
the  instruments  will  be  useless.  Use  a  good  grade  of 
oil,  applying  with  a  small  feather  or  broom  splint. 
Be  careful  not  to  put  on  too  much  oil. 

The  pens  become  worn  with  continued  use  on  the 
hard,  calendered  surface  of  the  bristol  board  and  there- 
fore must  be  sharpened  in  order  to  secure  fine,  smooth 
and  clean-cut  lines.  Some  draftsmen  send  their  pens 
to  be  sharpened  to  the  manufacturers  who  make  them, 
or  to  the  dealers  who  sell  them,  but  the  majority  prefer 
to  sharpen*  their  own,  as  very  little  time  is  required  for 
the  operation.  Extreme  care  must  be  used,  however, 
as  it  is  a  very  simple  matter  to  spoil  a  pen  by  not 
examining  it  frequently  during  the  process  to  see  how 
the  points  are  shaped. 

All  sharpening  should  be  done  on  a  fine,  close-grained 
oil  stone.  If  possible,  it  is  best  to  secure  one  which  is 
flat  enough  to  go  between  the  blades  of  the  pen  when 
they  are  screwed  apart,  so  that  if  during  the  sharpen- 


40 

ing  process  a  small  burr  should  form  on  the  inside  of 
the  blades  it  could  be  easily  removed.  No  sharpening 
should  be  done  on  the  inside  of  the  nibs,  however,  as 
this  would  spoil  the  pen. 

The  first  requirement  for  a  well-sharpened  pen  is  to 
make  the  blades  exactly  the  same  shape  and  length. 
To  do  this,  screw  the  blades  of  the  pen  together  until 
they  touch.  Then,  holding  the  pen  perpendicular  to 
the  face  of  the  oil  stone  with  the  thumb  screw  directly 
towards  or  away  from  you,  draw  the  blades  across  the 
stone,  tipping  first  to  the  right  and  downward,  then 
back  to  the  perpendicular,  and  then  to  the  left  and 
downward.  Repeating  this  operation  a  few  times  will 
not  only  make  the  blades  the  same  shape  and  length 
but  will  also  make  a  wTell-rounded  point.  However, 
this  process  makes  the  points  dull  and  you  will  be 
unable  to  make  fine  lines  until  the  edges  are  sharp- 
ened. For  this  part  of  the  operation  you  proceed  as 
follows : 

By  means  of  the  thumb  screw  open  the  blades  wide. 
Rub  one  of  the  blades  lightly  on  the  oil  stone,  directly 
from  and  then  towards  you.  Hold  the  pen  at  an  angle 
of  about  15°  with  the  surface  of  the  oil  stone  and  grad- 
ually increase  the  angle  during  the  process  until  an 
angle  of  30°  is  reached.  As  you  rub  the  blade  to  and 
from  you,  give  it  a  slight  twisting  movement  so  as  to 
keep  the  point  well  rounded.  Of  course,  the  same 
operation  is  required  for  the  other  blade.  Frequently 
examine  the  blades  and  when  the  points  appear  to  be 
fairly  sharp,  screw  them  together  and  draw  both  fine 
and  heavy  lines.  If  the  lines  are  not  smooth  and  clean 
cut,  sharpen  some  more  until  they  are.  Be  careful  not 
to  get  the  points  too  sharp  as  they  are  liable  to  cut  the 
surface  of  the  bristol  board.  If  the  ink  does  not  flow 
easily  rub  very  lightly  on  the  inside  of  the  blade,  as 
perhaps  a  small  burr  has  formed. 


CHAPTER  XI 

BLUE  PRINTING,  ETC. 

The  rules  of  the  U.  S.  Patent  Office  require  all  draw- 
ings to  be  filed  in  Washington,  and  when  they  are  once 
filed  they  cannot  be  returned.  Therefore,  it  is  always 
necessary  to  make  some  kind  of  a  copy  for  future 
reference.  Some  patent  attorneys  simply  have  their 
draftsmen  make  a  pencil  tracing  on  thin  paper,  which 
they  put  in  their  files  to  use  later  when  perhaps  some 
change  is  required.  However,  most  attorneys  use  the 
*blue  printing  process,  for  with  this  means  of  making 
copies  any  number  can  be  secured  at  very  little  cost. 
I  will  therefore  describe  this  operation. 

Blue  printing  is  the  means  of  duplicating  by  means 
of  the  action  of  light  on  sensitized  paper.  This  paper, 
called  blue-print  paper,  is  usually  furnished  the  drafts- 
man in  sheets  the  size  of  the  patent  drawing. 

A  frame  for  holding  the  drawing  and  blue-print 
paper  is  required.  This  frame  has  a  glass  front,  and 
a  removable  back  which  is  held  in  place  by  spring  clips. 

Before  starting  the  operation  of  blue  printing,  the 
bristol  board  on  which  the  drawing  is  made  should  be 
made  transparent  as  it  is  too  thick  for  the  light  to  pass 
through  easily.  This  is  done  by  placing  the  drawing 
in  a  tray  of  gasoline  and  allowing  the  bristol  board  to 
absorb  the  fluid.  When  the  paper  is  saturated  take  it 
from  the  tray  and  allow  it  to  drain. 

Remove  the  back  from  the  blue  print  frame  and 
place  the  drawing  on  the  glass  with  the  inked  side 
touching  the  glass.  A  sheet  of  the  sensitized  paper, 


42 

which  must  be  perfectly  dry,  is  placed  upon  the  draw- 
ing with  the  yellow  side  (sensitized)  touching  the  draw- 
ing. Smooth  the  paper  out  so  that  it  will  lie  perfectly 
flat  on  the  drawing,  and  fasten  the  back  in  place  with 
the  clips.  While  this  is  being  done  the  paper  should 
be  kept  from  the  light  as  much  as  possible.  The  frame 
is  then  placed  where  the  sun's  rays  can  shine  on  it 
directly.  If  convenient,  artificial  light  such  as  elec- 
tricity can  be  used. 

The  length  of  time  required  for  printing  varies  ac- 
cording to  conditions,  that  is,  whether  sky  is  clear  or 
cloudy;  or,  if  artificial  light  is  used,  varies  directly 
according  to  distance  from  light  and  strength  of  light. 

The  best  plan  is  to  expose  a  number  of  small  strips 
for  different  lengths  of  time  until  the  desired  color  is 
secured  and  then  record  the  time  allowed. 

The  print,  having  been  exposed  the  correct  length  of 
time,  is  taken  from  the  frame  and  placed  in  a  tray 
containing  clear  water.  The  print  should  be  removed 
in  some  dark  part  of  the  room,  away  from  any  window. 
It  should  then  be  placed  in  the  tray  with  the  yellow 
side  down,  and  care  should  be  taken  to  have  every  part 
covered  with  the  water.  Let  the  print  soak  for  about 
six  or  eight  minutes,  then  take  by  the  upper  corners 
and  lift  out  of  the  water.  Dip  it  back  again  and  repeat 
the  operation  until  it  appears  to  get  no  lighter.  Then 
remove  and  either  hang  up  or  lay  on  blotting  paper  to 
dry.  The  operation  can  be  repeated  for  as  many  prints 
as  desired. 

Some  attorneys  prefer  to  keep  for  their  records  a 
negative  from  which  prints  can  be  made  at  any  time. 

This  negative  is  secured  by  photographing  the  draw- 
ing on  bromide  paper,  and  from  the  bromide  any  num- 
ber of  positive  prints  can  be  secured  by  blue  printing 
as  before  described. 


CHAPTER  XII 
USEFUL  HINTS 

1.  Never  fill  the  pen  too  full. 

2.  Always  try  the  pen  on  the  margin  around  the 
drawing  to  see  that  you  have  the  desired  thickness. 

3.  Never  lay  your  pen  or  other  instruments  away 
without  thoroughly  cleaning  them. 

4.  Do  not  press  heavily  on  the  ruling  pen  as  it  will 
cut  the  surface  of  the  bristol  board. 

5.  Do  not  press  heavily  on  the  pencil,  so  that  if 
necessary  the  line  can  be  erased  and  no  indenture  will 
be  left  in  the  surface  of  the  paper. 

6.  Always  ink  your  section  lines  after  all  the  out- 
line is  completed. 

7.  Be  careful  not  to  get  ink  on  the  outside  of  the 
blades  of  your  ruling  pen.     It  is  sure  to  cause  a  blot 
as  you  draw  it  along  the  edge  of  the  tee-square  or 
triangle. 

8.  All  drawings  should  be  made  with  a  pen.    Never 
try  to  use  a  brush. 

9.  Never  use  anything  but  black  India  ink. 

10.  Do  not  use  both  hands  when  locating  the  needle 
point  of  compasses.     It  looks  awkward.     The  only  ex- 
ception is  when  the  lengthening  bar  is  used,  and  then 
it  is  necessary  to  employ  both  hands. 

11.  The  ink,  when  it  will  not  flow,  may  sometimes 
be  started  by  drawing  a  piece  of  paper  between  the 
ends  of  the  blades. 


44 

12.  Sometimes  just  moistening  the  end  of  the  finger 
and  touching  it  to  the  .points  will  start  the  ink. 

13.  Keep  the  threads    on    your    instruments  well 
oiled.     This  will  save  wear  on  the  threads  and  make 
the  screws  easier  to  adjust. 

14.  Never  ink  any  part  of    a  drawing  until    the 
drawing  has. been  entirely  penciled. 

15.  Be  particular  to  have  the  legs  of  the  dividers 
exactly  the  same  length  and  the  points  very  sharp  so 
that  holes  made  in  the  paper  when  spacing  are  very 
small. 

16.  Keep  the  drawing  board  away  from  heat  or  a 
damp  place  as  it  is  liable  to  warp. 

17.  Never  allow  a  coating  of  dry  ink  to  form  on 
the  points   of  the   pens.      Always   wipe   clean   when 
through  using. 

18.  Keep  the  drawing  paper  in  a  dry  place  and  be 
sure  it  is  laid  perfectly  flat.     It  is  a  good  idea  to  keep 
it  under  a  press  or  weight. 


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• 


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LD  62A-30m-2,'69 
(J6534slO)9412A— A-32 


General  Library 

University  of  California 

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LD  21-100m-2,'55 
(B139s22)476 


General  Library     . 
University  of  California 
Berkeley 


